Endo organ eistology Flashcards
General endocrine gland structure
Cellular components: Parenchyma= the functional tissue component of organs, in endocrine organs this component consists of hormone secreting cells
Stroma= the supportive tissue component of organs, in endocrine organs, this component is comprimised of connective tissue and fenestrated capillaties to disseminate synthesized hormone products
The pituitary gland- anterior
adenohypophysis
Secretes FSH, LH, ACTH, TSH, prolactin, GH, and B-endorphin (FLAT PiG). Melanotroponin (MSH) secreted from intermediate lobe of pituitary
From oral ectoderm alpha subunit (TSH, LH, FSH and hCG are the same) Beta is deffierent
Stains Blue
Very cellular in nature, Cells are chromophobes (Cp) with weakly staining cytoplasm- at the end of a secretory phase)
Chromophils with strong staining cytoplams (Acidophils and Basophils)
posterior pituitary
nuerohypophysis, stores and releases vasopressin (ADH), and oxytocin, both made in hypothalamus (supraoptic and PVN) and transported to post. pit via neurophysins (carrier protiens- derived from neuro ectoderm
Axon terminals called Herring bodies store antidiuretic hormone ADH and oxytocin synthesized by the hypothalamus
glial pituicytes P provide support for axon terminals
Anterior pituitary: Secretory granules present in the cytoplasm indicate cellular actitivity
Somatotrophs Acidophils secrete growth hormone
Mammotrophs (Acidophil and lactotrophs secrete prolactin
Corticotrophs (basophils) secrete ACTH
Thyotrophs (baso phils ) secrete TSH
Gonadotrophs (basophils) secrete FSH and LH
B-FLAT- Basophils- FSH, LH, ACTH, TSH
Acidophils- GH and PRL
Anterior Pituitary pars Intermedia
The pars intermedia is organized as irregular clusters of basophilic cells between the anterior pituitary and the posterior pituitary ( funtions to synthesize and secrete melanocyte simulating hormone)
The thyroid gland
a butterfly shaped gland located anterior to the upper portion of the trachea that secretes Iodine containing hormones, Triiodothyronin T3, or Thyroxine T4, Calcitonin
T 3 is more metabolically active than T4
Thyroid follicles
The thyroid gland stores inactive colloid in thyroid follicles which are surrounded by thyroid follicle cells, C cells and capillaries
Thyroid gland cellular composition
Thyroid follicle cells- contain colloid/thyroglobulin, become columnar in shape when active to remove stored colloid and convert it to T3/T4
Thyroid C cells or parafollicular cells are present as individualcells lining follicles or clumped between follicles they secrete calcitonin
The parathyroid glands
2 pairs on the posterior aspect of the thyroid gland, lying underneath its fibrous capsule
They secrete parathyroid hormone to regulate serum calcium and phosphate levels
Cell composition: Chief/principal cells (P) are intermixed with adipose tissue, they have strongly staining cytoplasm when actively secreting PTH
Oxyphil cells (O) are non secretory and increase in number with age
The adrenal glands
The adrenal glands are positioned at the at the upper poles of each kidney, and are composed of 2 types of endocrine tissues the adrenal cortex and the adrenal medulla
Cortex: : Zona Glomerulosa, Fasciculata, and Reticularis
GFR corresponds to Salt (mineralocorticoids), Sweet (glucocorticoids), and Sex (Androgens), The deeper you go the sweeter it gets
Adrenal cortex (Zona glomerulosa)
Outer most layer of the adrenal cortex
Secretory cells are arranged in rounded clusters separated by fibrous trabeculae, secrete mineralocorticoids (aldosterone) under the control of the RAAS system, Aldosterone acts on the kidney tubules to increase sodium reabsorption, and can result in increased water retention
The adrenal cortex zona fasiculata
The middle layer of the adrenal cortex, secretory cells populating this zone are arranged in columns separated by collagen strands
They secrete glucocorticoids (cortisol) which effect glucose metabolism and increase the breakdown of proteins, secretion of glucocorticoids is mediated by pituitary released ACTH
Adrenal cortex: Zona reticularis
The innermost layer of the adrenal cortex, adjacent to the medulla, secretory cells in this layer are irregularly arranged in branching cords and clusters with interspersed capillaries separating the clusters
They secrete large quantities of weak androgen precursors (DHEA) that can be acitvated to more potent androgens in target tissues
The adrenal medulla
Secratory cells are organized in clusters, responsible for catecholamine (epinephrine and norepinephrine) synthesis and secretion under the control of the sympathetic nervous system
The endocrine pancreas
the pancreas is primarily exocrine in function but contains isolated clusters of endocrine cells (islets of langerhans) surrounded by fibrous capsules located throughout its exocrine tissue
alpha cells- peripheral, make glucagon
beta cells- inside make insulin
delta cells- make somatostatin
